feat(frontend): Add delete key bindings to ReactFlow editor

(#11693)

Issues fixed by this PR
- https://github.com/Significant-Gravitas/AutoGPT/issues/11688
- https://github.com/Significant-Gravitas/AutoGPT/issues/11687

### **Changes 🏗️**

Added keyboard delete functionality to the ReactFlow editor by enabling
the `deleteKeyCode` prop with both "Backspace" and "Delete" keys. This
allows users to delete selected nodes and edges using standard keyboard
shortcuts, improving the editing experience.

**Modified:**

- `Flow.tsx`: Added `deleteKeyCode={["Backspace", "Delete"]}` prop to
the ReactFlow component to enable deletion of selected elements via
keyboard

### **Checklist 📋**

#### **For code changes:**

- [x] I have clearly listed my changes in the PR description
- [x] I have made a test plan
- [x] I have tested my changes according to the test plan:
- [x] Select a node in the flow editor and press Delete key to confirm
it deletes
- [x] Select a node in the flow editor and press Backspace key to
confirm it deletes
    - [x] Verify deletion works for multiple selected elements

autogpt_platform/frontend/src/app/(platform)/build/components/FlowEditor/Flow/Flow.tsx

@@ -99,6 +99,7 @@ export const Flow = () => {
           nodesDraggable={!isLocked}
           nodesConnectable={!isLocked}
           elementsSelectable={!isLocked}
+          deleteKeyCode={["Backspace", "Delete"]}
         >
           <Background />
           <CustomControls setIsLocked={setIsLocked} isLocked={isLocked} />

autogpt_platform/frontend/src/app/(platform)/build/stores/edgeStore.ts

@@ -115,10 +115,11 @@ export const useEdgeStore = create<EdgeStore>((set, get) => ({
           edge.data?.beadData ??
           new Map<string, NodeExecutionResult["status"]>();
 
-        if (
-          edge.targetHandle &&
-          edge.targetHandle in executionResult.input_data
-        ) {
+        const inputValue = edge.targetHandle
+          ? executionResult.input_data[edge.targetHandle]
+          : undefined;
+
+        if (inputValue !== undefined && inputValue !== null) {
           beadData.set(executionResult.node_exec_id, executionResult.status);
         }